Align Template-PSModule with module repository standard

[MariusStorhaug]

Problem

Template-PSModule does not match the caller and repository baseline defined in PSModule/Process-PSModule:

• .github/workflows/Process-PSModule.yml retains the previous workflow-level concurrency policy. It lacks the retained queue: max production policy and cannot provide the defined per-pull-request replacement behavior.
• The template lacks several files the PSModule repository standard lists as required, including CLAUDE.md, CODE_OF_CONDUCT.md, SECURITY.md, and SUPPORT.md.

Expected outcome

• Replace the caller with the standard two-job configuration: a non-pull-request job grouped by ref with queue: max, and a per-pull-request job with queue: single and cancel-in-progress: true.
• Reconcile the template file set with the PSModule repository standard, either by adding the required files or by updating the standard through the approved ownership path.

Verification

A repository created from the template has the documented caller behavior and passes the required repository-baseline checks without manual additions.